Hotroddinlogan

So I have a 4 door 2000 Jeep cherokee sport, with coil on plug ignition. And I has sat started on the regular. So just about a month ago I started it, and recorded it for my Youtube channel Hotroddinlogan ran it for about 15 minutes. And all of the sudden she shut off. It ran buttery smooth and didn't knock or shake. Just died out of the blue. I did not attempt to start it until the next morning. It did not want to start again, even at wide open throttle. Didn't even try. We have tried starter fluid with brand new autozone spark plugs. Again, didn't even try. It did not say on the dash "no bus" so its not the cpm. We did a spark test, it had spark but we are not sure how good the spark was in the broad daylight. But it did have some kind of spark. We have the spark plugs gapped to the stock gapping 0.35 and we have good fuel pressure. Help! This is a head banger.

agreen

Put a fuel pressure gauge on it. I saw that your other 6 posts are reviving 10 year old threads, and in one of them you said you didn't verify fuel pressure.

Hotroddinlogan

We did a fuel pressure test. Or somewhat of one. We pushed a knife into the schrader valve and got very strong fuel pressure. But I may have misspoken.

Hotroddinlogan

This is the last time it was seen running ok. I'm starting to think to is one of the three coil packs (aka the coil rail). We tested it with a really hot spark plug. It did have spark though. The last time it ran, it ran funny. It started no problem, after it ran for a couple minutes. But, the engine was hesitant to rev anywhere above about 1100 rpms. Than 5 minutes later it was hesitant to start. In fact, it didn't even run long enough for the starter to disengage from the motor's ring gear. That should be saying something. I later made a video for a school project and it ran. Again hesitated to rev up. Now above just about 2000 to 2500 rpms. But this time didn't think anything of it. I always heard these Jeep Xjs tend to fix themselves lol. Than off camera it shook for about 4 minutes and stopped. It then ran buttery smooth for the next 10-15 minutes and than died out of absolutely nowhere.

Dave51

Yeah that's meaningless. You need a number. Get a tester and do it right.

Dave51

And you have any error codes?

Hotroddinlogan

No, but it occasionally through a check engine light

Dave51

So what's the code for the check engine light?

Hotroddinlogan

Unfortunately we don't know

jpz

So you did a fuel pressure check with a knife on the Schrader valve, and you also don't know what the code is for occasional CEL that you get?

I think you need to do some more "actual" troubleshooting to get the best use of the knowledge on this or any forum. At this point, you are basically relying on Magic to fix your Jeep.

agreen

I went around and around in circles with a friend's 97 because he SWORE he had fuel pressure. Long story short, he ended up towing it to a mechanic who put 5 gal of gas in it and charged him for the gas and an hour of diagnostic time.

A Bluetooth ELM327 code reader is about $10. It's $24 for a fuel pressure gauge from Harbor freight. Otherwise, mechanic's hourly rates are about $100/hour. I'd say that even with those purchases you're still on top.

Hotroddinlogan

Okay, I did a fuel pressure test. We've got 39 lbs a fuel pressure at crank we will run the codes.

Hotroddinlogan

Thanks for the tips man! How much was he charged for the diagnosis.

jpz

39 seems on the low side to me. I believe the ideal PSI is closer to 49. I would think with 39 you would see a start a stall/rough idle though, but the fuel pressure might not be your "only" problem. Definitely get the CEL code and go from there, but keep in the mind that your fuel pressure appears to be below spec.

I would double check your fuel PSI. Maybe cycle the key a few times to see if you can build up enough pressure to reach 49 psi.

Dave51

Which fuel pump tester did you use? They can vary in accuracy.

So you sorta have spark, and sorta have fuel (pressure anyway). As noted in your response to another thread did you test these?

Do you have a multimeter?

Although hopefully the codes should reveal something. Are they still there or are they transient? My WAG is it's going to be a 1391. You should be able to monitor oxygen sensor activity with the ELM327 software.